Plotting board interchange circuit



w. E. INGERSON ETAL 3,196,446

PLOTTING BOARD INTERCHANGE CIRCUIT July 20, 1965 Original Filed March25, 1952 2 Sheets-Sheet 1 Pen,- /n Zerfrence 0r Overlays ATTORNEYS w. E.INGERSON H. G. OCH

J ly 1965 w. E. INGERSON ETAL 3,

PLOTTING BOARD INTERCHANGE CIRCUIT Original Filed March 25. 1952 2Sheets-Sheet 2 Manual Pen 4 6V.A.c. INVENTOR; 40 Ti 51 VVTET NaiRsomH.'G- OCH M w ATTORNEYS United States Patent 3,196,446 PLtlTlING BGARE)INTERCHANGE CIRQZUET Wiiliarn E. Inger-son, Watchung, and Henry G. Och,Madison, Ni, assignors, by rncsne assignments, to the United States ofAmerica as represented by the decretary of the Army Continuation ofapplication Ser. No. 278,354, Mar. 25, 1952. This application June 19,1964-, get. No. 391,350 8 Claims. (Cl. 346-8) This is a continuation ofapplication Serial No. 278,354, filed March 25, 1952.

The present invention relates to a plotting board for simultaneouslyplotting two-directional information of the positions of two movablepoints in space, such as the observed positions of two objects in space,or the observed posit-ion and the predicted, future position of oneobject in space.

More particularly the present invention relates to a control circuit forautomatically interchanging the information supplied to the two penmechanism of the plotting board in case of interference between the twopens or in case of predetermined lateral overlap of the two pens.

It is accordingly an object of the present invention to provide aplotting board and associated circuits for simultaneously plottingtwo-dimensional information concerning the positions of two movablepoints in space by means of two pen mechanisms without the risk ofinterference between the two pen mechanisms during operation thereof,

wherein the positions of the two movable points in space may correspondeither to the observed positions of tWo objects in space, or theobserved position and the predicted, future position of one object inspace.

It is another object of the present invention to provide a peninterchange switching circuit which interchanges automatically the datasupplied to the respective pen mechanisms during the course of plottingin case of interference between the pens.

It is another object of the present invention to provide an automaticswitching circuit to interchange automatically the data supplied to therespective pen mechanism during the course of plotting in case ofpredetermined lateral overlap between the pens.

It is still a further object of the present invention to provide anautomatic switching circuit to interchange automatically the datasupplied to the respective pen mechanisms during the course of plottingwhich is simple in structure and reliable in operation.

It is another object of the present invention to provide an automaticswitching circuit to interchange either manually or automatically thetwo-dimensional informations corresponding to two moving points suppliedto the respective pen mechanisms of the plotting board by using anelectronic trigger circuit to initiate the switching mecharnsm.

It is another object of the present invention to provide an automaticswitching circuit for interchanging the data corresponding to thetwo-dimensional informations of the positions of two points in spacesupplied to the respective pen mechanisms of the plotting board in sucha manner as to first move apart and separate the plotting arms by firstinterchanging the data corresponding to one dimension and thereafterinterchanging the data corresponding to the other dimension.

It is a still further object of the present invention to provide anautomatic switching circuit including an electronic trigger circuit forinterchanging the data supplied to the two pen mechanisms of theplotting board wherein the trigger circuit includes a delay circuit toprevent immediate reoperation of the trigger tube through accidentalcontact between the two pens while the initial interference,

3,196,446 Patented July 20, 1965 ice which had operated the triggercircuit, is still being relievcd.

T he specific nature of the invention as well as other objects andadvantages thereof will be obvious from the following description takenin connection with the accompanying drawings which show for purposes ofillustration only one specific embodiment of the present invention andwherein:

FIGURE 1 shows schematicaly the plotting board including the penmechanisms in accordance with the present invention;

FIGURE 2 is a block diagram showing the overall operation of the systemin accordance with the present invention;

FIGURE 3 represents the circuit diagram of the pen interchange relaypanel and the trigger circuit in accordance with the present invention.

Referring more particularly to the drawings where like reference numeralare used to designate like parts in the various figures thereof,reference numeral 1 illustrates the plotting board as shown in FEGURE 1,on which are schematically indicated by dotted lines 2 and 2' the blocksrepresenting respectively the left and right pen mechanisms. Each penmechanism includes a pen 3 and 3 mounted on pen supports 4 and 4respectively. The left pen 3 is driven in the vertical direction bymotor 5 through motor shaft 6, reduction gearing mechanism 7, connectingshaft 3 and drive pulley 9 which is rigidly secured to shaft 3 in anyconventional manner as by keying or press-fit. Belt lb fastened at bothits ends 11 and 12 to pen support 4 passes over drive pullley 9 and isdriven thereby in an upward or downward direction depending on thedirection of rotation of reversible motor 5. Reference numeral 13designates a driven pulley over which passes belt 1i). Shaft 14 issecured to pulley 13 in any conventional manner as by keying orpress-fit and drives a reduction gearing mechanism 15', which in turndrives the movable arm of potentiometer-follower 16 through shaft 17.The input to motor 5 is denoted as Y since motor 5 moves the left pen 3in the vertical or Y direction. The output from potentiometer-follower16 is denoted as F since the voltage derived from the movable arm towhich the output lead is electrically connected corresponds to thevertical position of the left pen 3.

Similarly the right pen 3' is driven in the vertical direction by motor5 through motor shaft 6', reduction gearing mechanism 7 connecting shaft8 and drive pulley 9 which is rigidly secured to shaft 8' in anyconventional manner as by keying or press-fit. Belt 16 fastened at bothits ends ll and 12 to pen support 4 passes over drive pulley 9 and isdriven thereby in an upward or downward direction depending on the senseof rotation of motor 5'. Reference numeral 13 designates a driven pulleyover which passes belt 10. Shaft 14' is secured to pulley 13' in anyconventional manner as by keying or press-fit and drives reductiongearing mechanism 15', which in turn drives the movable arm ofpotentiometer 15 through shaft 17'. The input to motor 5' is denoted asY since motor 5 moves the right pen 3' in the vertical or Y direction.The output from potentiometer-follower i6 is denoted as F since thevoltage derived from the movable arm to which the output lead iselectrically connected corresponds to the vertical position of the rightpen 3. In order to prevent slippage between belt it and driven pulley 13and between belt it) and driven pulley 13 any conventionalbelt-tightening device (not .shown) may be incorporated in both verticalpen driving mechanisms.

Pen mechanisms 2 and 2' are carried by arms 18 and 18 respectively whichmove the same in a horizontal or X direction. Motors 1% and 19' drivereduction gearing mechanisms 2d and 2% through motor shafts 21 en agesoutput of reduction gearing mechanisms 2t? and 29 to drive pulleys 23and 23 respectively to which shafts 22 and 22 are secured in anyconventional manner as by keying or press-fit. Belts 24 and 24' whichare fastened to arms 18 and 18 at their respective ends 25, 2e and 25,2a pass over drive pulleys 23 and 23' and the driven thereby. Belts 2dand 2 1 also pass over driven pulleys 2'7 and 27' to which are securedshafts 28 and 28' which drive the movable arms of followerpotentiometers 29 and 29' through reduction gearing mechanisms 3d and3t) and connecting shafts 3i and 31'. Attached to arms 18 and 18 arecontacts 32 and 32 shown herein for purposes of illustration as knifeedges, of which contact 32 is bent to protrude in a direction out of thedrawlng while contact 32 is bent to extend in a direction into thedrawing. The trigger control circuit denoted as TC. is electricallyconnected to contact 32 and to pen 3 whereas contact 32' and pen 3 areelectrically connected to ground so that ground is applied to triggercontrol circuit TC. in the case of interference between pens 3 and 3' orin the event of excessive overlap of arms 18 and 18' determined only bythe particular mounting and shape of contacts 32 and 32. The effect ofgrounding trigger control circuit T.C. will be more fully describedhereinafter with reference to FIGURE 3. The input to motor 19 is denotedas X since motor 19 moves the left pen mechanism 2 in a horizontal or Xdirection, while theinput to motor 19 is denoted as X since motor 19moves the right pen mechanism 2 in a horizontal or X direction. Theoutput from potentiometer-follower 29 is denoted as F since the voltagederived from the movable arm of potentiometer 2? to which the outputlead is electrically connected corresponds to the horizontal position ofthe left pen mechanism 2, while the output from potentiometcnfollower 2?is denoted as F since the voltage derived from the movable arm ofpotentiometer 2d to which the output lead is connected corresponds tothe horizontal position of the right pen mechanism 2. In order toprevent slippage between belt 24 and driven pulley 27, and between belt24 and driven pulley 27 any conventional belt-tightening device (notshown) may be incorporated in both horizontal pen driving mechanisms.Potentiometer-followers 16, f6, 29 and 29 may be energized from a directcurrent power source (not shown) in any conventional manner. It isfurther understood that appropriate limit switches may be incorporatedin both pen mechanisms 3 and 3 to limit the movements thereof in boththe vertical and horizontal directions.

1 FIGURE 2 illustrates in block diagrammatic form one possiblearrangement of the overall system for use with the pen interchange relaysystem in accordance with the present invention. More particularlydotted blocks 33 and 33' represent two observing posts for obtainingtwodimensional informations of two moving objects, the movement of whichis to be plotted independently on plotting board 1, and for transmittingelectrical signals S ands, corresponding to such two-dimensionalinformations from observing posts 33 and 33' to computers 34 and 34'.

One specific embodiment fulfilling the requirements of such observationposts is shown with respect to block 33 which comprises a telescope 35rotatably mounted in azimuth by means of bracket 35 on shaft 36 which isrigidly secured to the movable arm 37 of potentiometer 38; the terminalsof potentiometer 38 are connected to a conventional source of directcurrent power supply (not shown). Shaft 36 is supported in pedestal 39which may include suitable bearings (not shown). It is thus clear thatthe signal voltage S in the output lead from observing post 33 which iselectrically connected to the movable arm 37 through shaft as, dependson the position in azimuth of telescope 35. Since observing post 33 issimilar to post 33 in construction and function the details blocks 49and 41 are indicated in dotted lines.

thereof are not shown or described herein. Signal volttages S and S arerepresentative of the distances of the observed objects and may beobtained in any conventional manner as is known in connection with priorart range finders, such as optical range finders or radar systems. It iswell understood however that any other optical or electrical systemssuch as radar systems, may be substituted for the one presently shownand described with reference to posts 33 and 33'. The computer outputscomprise signals S and 8 corresponding to the two-dimensionalinformation S from observation post 33, and signals 5 and 8corresponding to the two-di mensional information S from observationpost 33. While we have shown posts 33 and 33' for observation of twoobjects in space, it is understood however that the information from onepost may be used only for plotting present and predicted, futurepositions of one object only. This may be accomplished in its simplestform, for instance, by utilizing the signal voltages S and S and bypassing them through appropriate circuits to determine the future,predicted position of such object so that signal voltages 8 and S thencorrespond to the predicted future position of the object observed bypost 33. Trigger circuit 41 which itself is actuated by trigger controlcircuit T.C. as a result of pen interference or pen overlap is connectedto pen interchange relay panel 40 as will be more fully described withreference to FIGURE 3. The two signal outputs channels X Y and X Ycorresponding to signals S Sy and signals 8 8 or vice versa, asdetermined by the particular position of the pen interchange relay panel40, are fed through appropriate amplifier stages 42 to motors 19, 5, f9and 5 as shown in both FIGURES 1 and 2. The signal outputs F F and F Ffrom potentiometer followers 29, 16 and 29', 16' are fed back as errorvoltages to an1plifiers 42.

The details of pen interchange relay panel 40 and of trigger circuit 41are illustrated in FIGURE 3 wherein Trigger circuit 41 comprises atrigger tube 43 which may be of the thyratron type as, for example, atetrode thyratron tube type 2050, which includes a cathode 44, a plateor anode 45, a first control grid'dd and a second control grid 47electrically connected to cathode 44, the latter being connecteddirectly to ground. The output circuit connected to plate includes inseries a trigger relay 48 and the secondary winding of transformer 49,which is connected to ground at its end opposite trigger relay 43; theprimary of transformer 49 is connected to a commercially availablealternating current power source. The input circuit of trigger tube 43connected to control grid 46 comprises in series a delay network, whichconsists of the parallel circuit of resistor 50 and of capacitor 51, andgrid leak resistor 52. Trigger control circuit T.C. is connected to thejunction between the delay circuit and grid leak resistor 52 so thatground is applied to control grid through pens 3 and 3' in case of peninterference or through contacts 32 and 32' in case of overlap of arms18 and 13'. In order to provide appropriate negative bias on grid as asource of direct current voltage B- is applied to theaforementionedjunction through resistor 53, which together with grid leak resistor 52constitutes a bleeder circuit for the negative power supply 13-. Triggerrelay 48, which is of the slow-release type, comprises a normally opencontact 54 which is connected to ground. The stationary contact 54thereof is connected to one side of the energizing coils of relays 55and 56 through normally closed contacts 57 and .relays 55 and 56 beingarranged in a so-called WZ circuit as will be more fully describedhereinafter. The other side of the coils of relays 55 and 56 areconnected to B- through current limiting resistors 58 and 59. Manual peninterchange switch S is connected in parallel with contacts 54 and 54".

Relay 55 operates two single-pole, single-throw conarcades d tacts ofwhich the two normally open, movable contacts 69 and 61 are bothconnected to ground. Stationary contact 60' is connected to one side ofthe coils of relays 55 and 56 while stationary contact 61 applies groundto certain parts of the pen interchange relay panel it) upon operationof relay 55 as will he more fully described below. Relay 56 is of thesingle-pole, double-throw type with the movable arm 62 normally makingcontact with stationary contact 62 which is connected to the junctionbetween the other side of the energizing coil of relay s and resistor59. The other stationary contact 62" is connected to the junctionbetween the other side of the coil of relay 55 and resistor 58.

The pen interchange relay panel as comprises four input'terminals 63,64-, 65 and 66 four output terminals 67, 63, 69 and 7h. The outputsignals S and 8 from computer 34 are applied to input terminals 63 and64, and the output signals 3 and S from computer 34' to terminals 65 and66 respectively. Signals X Y X and Y R are fed from output terminals 67,63, 69 and 7% after appropriate amplification in amplifiers 42 to motors19, 5, 19 and 5 respectively. Relay panel ill further comprises threerelays 71, 72 and 73 of which relay 72 is of the slow release type. Theenergizing coil of relay 71 is connected at one end to the negativepower supply B through current limiting resistor 74 and at the other endto stationary contact 61' in the trigger circuit 431. R lay '71 operatesthree single-pole, double-throw contacts 75, 76 and 77 respectively andone single pole, singlethrow contact 78. Movable contact 75 is connectedto input terminal as and normally rests against stationary contact 75'which is connected to output terminal 67 thereby establishing a circuitbetween input terminal 63 and output terminal 67 with relay 71deenergized. Movable contact 76 is connected to input terminal 65 andnormally rests against stationary contact 75" which is connected tooutput terminal 69, thereby establishing a circuit between inputterminal 65 and output terminal 69 with relay 71 deenergized. Stationarycontact 76' is connected in parallel with stationary contact 75, andstationary contact 75" in parallel with stationary contact 76". Movablecontact 77 which normally rests against stationary contact 77" andmovable contact 78 which is normally open are both connected to ground.Relay 73 operates four single-pole, double-throw contacts 7%, 8t 81 andS2 and one single-pole, single throw contact Movable contact 79 isconnected to the control grid 46 of trigger tube 43 through isolatingresistor S9, stationary contacts 79' and 79" being connected tostationary contacts 77 and 77' respectively. Movable arm'St is connectedto input terminal 64- and normally rests against stationary contact 36'which is connected to output terminal 63 thereby establishing a circuitbetween'input terminal 64 and output terminal 68 with relay 73deenergized., .Movable arm 81 is connected to input terminal andnormally rests against stationary contact 81" which is connected tooutput terminal 7t thereby establishing a circuit between input terminal66 and output terminal 74 with relay 73 deenergized.- Stationary contact89 is connected in parallel with stationary contact 81", and stationarycontact 81' in parallel with stationary contact 86'. Movable contact 82is connected to one side of a six volt, alternating current powersupply, the other side of which is connected directly to green. lamp84and red lamp 85. Movable contact 82 normally rests against stationarycontact 82" thereby establishing a circuit for lighting green lamp 84with relay 73 deenergized thus indicating normal operation. Movablecontact 83, which is normally open is connected to movable contact 78.The energizing coil of relay 73 is connected at one end thereof to thedirect current power supply B through current limiting resistor 86. Theenergizing coil of relay 72 is connected at one end to the directcurrent power supply through current limiting resistor 87, the other endbeing connected to resistor 8h in the grid circuit of trigger 6 tube 43.Relay '72 operates one single-pole double-throw contact the movablecontact 83 of which is connected in parallel with movable contact 78 andnormally rests against stationary contact 85' which is connected toground. Stationary contact 38" is connected to the other end of theenergizing coil 73.

Operation Signal voltages S and S from observing posts 33 and 33' areapplied to computers 3 and 34' respectively during the tracking of themoving objects and are representative of the two-dimensional positionsthereof. Computers 34- and 34- resolve signals S and S into theirvertical and horizontal components 8 5 and 8 and 8 respectively whichmay selectively represent present or predicted positions or" the twomoving objects as is well-known in the art of computers. Signal S isapplied to terminal 63, signal 5 to terminal 64-, signal S to terminal65, and signal 5 to terminal 66 of pen interchange relay panel 44 Thesignals X Y X and Y from output terminals er, 68, 69 and energize motors19, 5, l9 and 5 respectively after appropriate amplii cation inamplifiers 42. Motors 19 and 19' drive pen mechanisms 2 and 2 in thehorizontal direction in accordance with signals X and X corresponding tosignals S and 8 respectively during normal operation of pen interchangerelay panel 4%. Likewise motors 5 and 5 drive pens 3 and 3 in thevertical direction in accordance with signals Y and Y 3 corresponding tosignals 8 and S respectively during normal operation of pen interchangerelay panel ill.

Control grid as of trigger tube 2-3 is normally biased to approximately4 volts through bleeder circuit con sisting of resistors 53 and 52,which prevents it from firing, so that relay it; is normally unoperated.However when interference between pens 3 and 3' or interference betweenarms 18 and 3% as a result of lateral pen overlap in excess of 1.75inches occurs, ground is applied to trigger control circuit TC. throughcontact between pens 3 and 3 or through contact between knife-edgecontacts 32 and 32'. Control grid 4-6 of trigger tube 4-3 to whichtrigger control circuit TC. is connected, is thus grounded when pen orarm interference takes place, thereby firing tube 43 during the nextsucceeding cycle of positive voltage applied to plate 4-5 throughtransformer 4-9 and the coil of relay 48. The resulting plate currentoperates relay 4-8 which closes its contacts 54- and 54-. A ground isthus applied via contacts 54-, 54 of relay 48 to contact 57 of relay 55and to contact 62 of relay 55. This ground is then applied over contacts57, 6d of relay 55 to the coil of normally deenergized relay 55, whichconsequently operates since one side of the direct current power sourceB is also connected to ground. Although this ground is also applied tothe energizing coil of relay 56, it does not operate since its coil isshort-circuited by its contacts 62, 62 and contacts 54, 54' of relay 43.Operation of relay 55 results in closure of contacts 6t) and tillimmediately followed by opening of contacts on 57, contacts 6t 6t? and57 being of the make-before-break type. Closure of contacts on and 6t?continues the ground on the coil of relay 55, and applies an independentground to energizing coil of relay 56 so that the latter will beenergized upon deenergization of relay 48. Operation of relay 55 alsoapplies ground to relay 71 of the pen interchange relay panel 5% overcontacts er and 61 hereby operating normally deenergized relay 71. Relay72 which is normally energized by application of a ground to itsenergizing coil over contacts 77 and 77 of relay 71 and contacts 79' and79 will be dee ergized upon operation of relay 71 which breaks thecircuit between contacts 77 and 77" and establishes a circuit betweencontacts 77 and 77. Relay 72 is of the slow release type, however, andtakes a period .4 second to release. Gperation of relay 71 connectsoutput terminal as to input terminal as over eases-ac contacts 76' and7d, and outpute tcrimnal 69 to input terminal 63 over contacts 75' and75, thereby interchanging the signals applied to motors 1? and 1%whereby pen mechanisms 2 and 2 are moved apart laterally. Afterexpiration of the period of .4 second, relay '72 will become deenergizedthereby establishing a ground for the coil of normally deenergized relay73 over contacts '78 and 78 and contacts 83 and 323, which causes relay73 to energize. Operation of relay 73 extinguishes the green lamp 84indicative of normal operation and causes red lamp 535 to be lightedover contacts 82 and 82.

Operation of relay 73 connects output terminal 68 to input terminal asover contacts 31 and iii, and output terminal 7d to input terminal 1over contacts 8i) and 8%, thereby interchanging the signals applied tomotors 5 and 5' whereby pens 3 and 3 are now also moved apart in thevertical direction. It is thus clear that the interchange of the inputsignals to the motors 19 and 5, and 1% and 5 of the left and right penmechanisms 2 and 2 will relieve the pen or arm interference. Operationof relay 73 also reestablishes a ground connection to the energizingcoil of relay 72 over contacts 79 and 79 of relay 73 and contacts 77'and 77 of relay 71 whereby relay '72 is again operated. However theground on the coil of relay 73 is continued over its contacts 83' and 33and contacts 73 and 78 of relay 71.

This sequence of operation interchanges the data first and thus permitsploting arms 18 and 18' to move apart and separate before the Y data areinterchanged. As soon as the interference is relieved whereby ground isremoved from trigger control circuit TO, the negative bias is restoredto the grid as of the trigger tube 33, and as soon as its plate voltagereaches zero on the alternating current cycle, it will cease to pass theplate current thereby deenergizing relay 4% which opens the ground oncontact 54'. As soon as the ground is removed from contact 54' theshort-circuit via contacts 62 and 62 across the energizing coil of relayso is removed, whereupon relay 55 is energized over contacts as and oil"of relay 55 which continues to be energized over its self-lockingcircuit comprising contacts 6t! and 60. Operation of relay 56establishes a circuit between contacts 54 and the side of resistor 58connected to the coil of relay 55 over contacts 62 and 62 therebypreparing the so-called WZ circuit for the next cycle of operation incase of another pen or arm interference. it is to be noted that both relays 55 and 56 remain energized under these conditions over contacts 60and 6t) whereby the ground circuit is continued for relay 71 overcontacts 61 and 61 so that relays 71, 72 and 73 also remain energizedafter completion of the aforementioned sequence of operation of triggercircuit 41 and pen interchange relay panel 40. Furthermore in order toprevent an immediate reoperation of trigger tube 413 through accidentalcontact of the pens 3 and 3 or contacts 32 and 32 while the initialinterference is relieved, the delay circuit consisting of the parallelarrangement of resistor Eli and capacitor 51 is connected in the gridcircuit 46, the operation of which is obvious from a consideration ofthe typical values of the circuit parameters which may be as follows:

R =1 megohm. C =1 microfarad. R =1l kilohms. R =.25 megohm. R =1 megohm.

A subsequent interference will again operate relay 48 as explained aboveand apply ground to contact 54 from contact as. Contact 54 however isnow connected to resistor 58 at its connection with the coil of relay 55over contacts s2 and 62" thereby short-circuiting the coil of relay 55which will drop out. Deenergization of relay 5 will open the circuitbetween contacts 61 and 61 thereby removing the ground from relay '71 ofthe pen in interchange relay panel 40. The ground applied to contact 66)from contact on will also be removed upon operation of relay 55. Howeversince contacts 60, and 57 are of the make-before-break type, ground willbe continued on coil of relay 56 over contacts 54 and 54' of relay 4%and contact 57 and 6d of relay 55 as long as the interference continuesenergization of relay 48. Since relay 55 remains energized, theenergizing coil of relay 55 remains short circuited over contacts 62 and62" thereby preventing operation of relay 55.

Deenergization of relay 71 as a result of deenergization of relay 55again connects output terminal 67 to input terminal 63 over contacts 75'and 75, and output terminal 69 to input terminal 65 over contacts 76 and76, thereby again interchanging at first the signal voltages applied tomotors 19 and 19' whereby pen mechanisms 2 and 2' are moved apartlaterally. Removal of the ground from contact 77" will deenergize relay72, which will drop out after a period of .4 second, thereby removingthe ground connection from the coil of relay 73 over the self-lockingcircuit comprising contacts 83 and 83. Deenergization of relay 73 againconnects output terminal 68 to input terminal 64 over contacts 89' and3%, thereby again interchanging the signal voltages applied to motors 5and 5 whereby pens 3 and 3' are moved apart in the vertical direction.It is thus seen that the X data is again interchanged first therebypermitting the plotting arms 18 and 18 to move apart and separating thearms before the Y data are interchanged. Upon deenergizatio-n of relay73, red lamp '85 is extinguished and green lamp E54 lighted overcontacts 82 and 32" thereby indicating again normal operation.Deenergization of relay 73 will also establish an energizing circuit forrelay 72 which may be traced from ground over contacts 77 and 77" ofrelay 71 and contacts 79' and 7-9 of relay 73 to the coil of relay 72.Relay 72 will thereafter assume its normally energized condition inpreparation for the next cycle of operation.

Upon deenergization of relays 71 and 73, followed by an interchange ofthe signals representing the X and Y data of the two moving objects theinterference will again be relieved, thereby removing ground fromcontrol grid 46 of trigger tube 45 and deenergizing relay 48 asexplained above. Deenergization of relay 48 will open contacts 54 and 54thereby removing ground from the coil of relay 56 which willconsequently drop out. This trigger circuit 41 and pen interchange relaypanel 40 are again readied for another cycle of operation with relays48, 55 and 56 as well as relays 71 and 73 deenergized and with onlyrelay 72 operated which are the normal operating conditions of theserelays. Operation of manual pen interchange switch S would have the sameeffect on the circuits as energization of relay 48 as a result ofinterference, and the sequence of operation is therefore not describedherein.

As pointed outabove, the pen interchange relay system in accordance withthe present invention is not limited to the particular embodiment ofplotting the observed positions of two objects in space as illustratedherein, but may be equally used to plot present, observed position andpredicted, future position of one and the same object or target.Furthermore, the present pen interchange relay system is not limited inits application to a plotting board for plotting Cartesian coordinatesbut is equally applicable for use with other coordinate systems, suchas, for example, polar coordinates and cylindrical coordinates.

While We have shown and described only one preferred embodiment of ourinvention it will be obvious to those skilled in the art that it is notso limited, but is suscepw tible of various other changes andmodifications without departing from the spirit thereof, and We desire,therefore, that only such limitations shall be placed thereupon as areimposed by the prior art or as are specifically set forth in theappended claims.

arse-ga e We claim:

1. In combination with a plotting board capable of simultaneouslyplotting two-dimensional information of the positions of two points inspace including two pen mechanisms, each operated independently inaccordance with signals representative of said two-dimensionalinformation of one of said two points, a pen interchange control circuithaving two input and two output channels for interchanging theconnections between respective input and output channels, each of saidoutput channels being connected to one of said pen mechanismsrespectively, a normally inoperative trigger circuit, means foroperating said trigger circuit in response to interference between saidpen mechanism, circuit means between said trigger circuit and saidcontrol circuit operative in response to operation of said triggercircuit for interchanging the connections between respective input andoutput channels, and means for applying a signal representative of theposition of one of said points to each of said input channels, saidcircuit means including delay means for delaying the interchange of thesignals in each channel representative of one dimension with respect tothe signals representative of the other dimension.

2. A control circuit for interchanging the signals between the inputcircuits and corresponding output circuits thereof in response to theoccurrence of a predetermined condition in said output circuitscomprising normally inoperative first relay means, trigger meansoperative in response to the occurrence of said condition for energizingsaid first relay means, normally inoperative second relay meansoperative in response to energization of said first relay means,normally inoperative third relay means, normally inoperative fourthrelay means, normally inoperative fourth relay means operated inresponse to energization of said second relay means, normallyinoperative fifth relay means operated in response to energization ofsaid fourth relay means, delay means interconnected between said fourthand fifth relay means to delay energization of said fifth relay means,means responsive to operation of said fourth and fifth relay means fordeenergizing said first relay means and for energizing said third relaymeans.

3. A control circuit for interchanging the signals between the inputcircuits and corresponding output circuits thereof in response to theoccurrence of a predetermined condition in said output circuitscomprising first relay means, a trigger means operative in response tothe occurrence of said condition for energizing said first relay means,normally inoperative second and third relay means, said second relaymeans being operated in response to energization of said first relaymeans, normally inoperative third relay means, fourth relay meansoperative in response to energization of said second relay means, fifthrelay means operative in response to energization of said fourth relaymeans, delay means interconnected between said fourth and fifth relaymeans to delay energization of said fifth relay means by a predeterminedtime, and means to energize said third relay means in response toenergization of said fifth relay means, said signals being interchangedby operation of said fourth and fifth relay means.

4. A control circuit for interchanging the signals between two inputchannels and two output channels in response to the occurrence of apredetermined condition in said output channels comprising a normallyquiescent trigger tube, means responsive to occurrence of said conditionfor energizing said trigger tube, a normally deenergized first relayenergized in response to energization of said trigger tube, a normallydeenergized second relay energized in response to energization of saidfirst relay, a normally deenergized third relay, a normally deenergizedfourth relay energized in response to energization of said second relay,a normally energized delay relay deenergized a predetermined time afterenergization of said fourth relay, a normally deenergized fifth relayenergized in response to deenergization of said normally energized delayrelay, first circuit means responsive to energization of said fifthrelay for consecutively reenergizing said delay relay and forconsecutively deenergizing said trigger tube and said first relay,second circuit means for energizing said third relay in response to saidlastmentioned deenergization, third circuit means responsive to.reoccurrence of said condition for consecutively reenergizing saidtrigger tube and said first relay and for consecutively deenergizingsaid second relay and said fourth relay, and fourth circiut meansresponsive to deenergization of said fourth relay for deenergizing saidclay relay and for consecutively deenergizing, after expiration of saidpredetermined time, said fifth relay, said trigger tube, said firstrelay and said third relay, said signals being interchanged uponoperation of said fourth and fifth relays.

5. In combination with a plotting board capable of simultaneouslyplotting two-dimensional information of two movable points including twopen mechanisms, each operated independently in accordance with theinformation of a respective one of said points, a pen interchangecircuit arrangement for interchanging the signals applied to said twopen mechanisms upon the occurrance of interference therebetweencomprising two input channels and two output channels, a normallyquiescent trigger tube, means responsive to occurrence of saidinterference for energizing said trigger tube, a normally deenergizedfirst relay energized in response to energization of said trigger tube,a normally deenergized second relay energized in response toenergization of said first relay, a normally deenergized third rela' anormally deenergized fourth relay energized in response to energizationof said second relay, a normally energized delay relay deenergized apredetermined time after energization of said fourth relay, a normallydeenergized fifth relay energized in response to deenergization of saidnormally energized delay relay, first circuit means responsive toenergization of said fifth relay for consecutively reenergizing saiddelay relay and for consecutively deenergizing said trigger tube andsaid first relay, second circuit means for energizing said third relayin response to said last-mentioned deenergization, third circuit meansresponsive to reoccurrence of said interference for consecutivelyreenergizing said trig er tube and said first relay and forconsecutively deenergizing said second relay and said fourth relay, andfourth circuit means responsive to deenergization of said fourth relayfor deenergizing said delay relay and for consecutively deenergizingafter expiration of said predetermined time said fifth relay, saidtrigger tube, said first relay and said third relay, said signals beinginterchanged upon operation of said fourth and fifth relays.

6. The combination comprising a plotting board, two pen mechanismsoperable on said board to indicate the positions of two points in space,means for driving said pen mechanisms, a pen interchange control circuitcomprising two input and two output circuits and means for interchangingthe connections between respective input and output circuits, each ofsaid output circuits connected to one of said pen mechanism drivingmeans, means for applying signals representative of the positions of thesaid points in space to each of the said input circuits, a normallyinoperative trigger circuit connected to said pen interchange controlcircuit, and means for operating said trigger circuit in response tocontact between said pen mechanisms on said board whereby the said peninterchange control circuit changes the connections between therespective input and output circuits to thereby remove pen mechanisminterference, said trigger circuit including a delay circuit comprisinga parallel arrangement of a resistor and a capacitor to preventreoperation thereof through accidental contact between the said penmechanisms while said pen mechanism interference is removed.

7. The combination comprising a plotting board, two

sneaaae 1 '1 pen mechanisms operable on said board to indicate thepositions of two points in space, electrical motors connected to drivethe said respective pen mechanisms, a pen interchange control circuitcomprising two input and two output circuits and a plurality of relaysconnected to interchange the connections between respective input andoutput circuits, each of said output circuits connected to respectiveones of said electrical motors, computers connected to each of the saidinput circuits and adapted to apply thereto signals representative ofthe positions of the said two points, a normally inoperative triggercircuit including a vacuum tube connected to said pen interchangecontrol circuit relays, a contact on each said pen mechanisms foroperating said trigger circuit in response to engagement therebetweenwhereby the said pen interchange control circuit relays change theconnections between the respective input and output circuits to therebyremove pen mechanism interference, and a delay circuit comprising aparallel arrangement of a resistor and a capacitor connected to the gridof said trigger circuit vaccum tube to prevent reoperation of saidtrigger circuit through accidental engagement between the said penmechanism contacts while said pen mechanism interference is removed.

8. The invention made in accordance with claim 7 wherein the said vacuumtube is a thyratron.

References Cited by the Examiner UNITED STATES PATENTS 2,714,047 7/55Dehmel u 346-8 LEYLAND M. MARTIN, Primary Examiner.

1. IN COMBINATION WITH A PLOTING BOARD CAPABLE OF SIMULTANEOUSLYPLOTTING TWO-DIMENSIONAL INFORMATION OF THE POSITIONS OF TWO POINTS INSPACE INCLUDING TWO PEN MECHANISMS, EACH OPERATED INDEPENDENTLY INACCORDANCE WITH SIGNALS REPRESENTATIVE OF SAID TWO-DIMENSIONALINFORMATION OF ONE OF SAID TWO POINTS, A PEN INTERCHANGE CONTROL CIRCUITHAVING TWO INPUT AND TWO OUTPUT CHANNELS FOR INTERCHANGING THECONNECTIONS BETWEEN RESPECTIVE INPUT AND OUTPUT CHANNELS, EACH OF SAIDOUTPUT CHANNELS BEING CONNECTED TO ONE OF SAID PEN MECHANISMSRESPECTIVELY, A NORMALLY INOPERATIVE TRIGGER CIRCUIT, MEANS FOROPERATING SAID TRIGGER CIRCUIT IN RESPONSE TO INTERFERENCE BETWEEN SAIDPEN MECHANISM, CIRCUIT MEANS BETWEEN SAID TRIGGER CIRCUIT AND SAIDCONTROL CIRCUIT OPERATIVE IN RESPONSE TO OPERATION OF SAID TRIGGERCIRCUIT FOR INTERCHANGING THE CONNECTION BETWEEN RESPECTIVE INPUT ANDOUTPUT CHANNELS, AND MEANS FOR APPLYING A SIGNAL REPRESENTATIVE OF THEPOSITION OF ONE OF SAID POINTS TO EACH OF SAID INPUT CHANNELS, SAIDCIRCUIT MANS INCLUDING DELAY MEANS FOR DELAYING THE INTERCHANGE OF THESIGNALS IN EACH CHANNEL REPRESENTATIVE OF ONE DIMENSION WITH RESPECT TOTHE SIGNALS REPRESENTATIVE OF THE OTHER DIMENSION.